Reflecting optical system



July 30, 1935. H. P. GAGE REFLECTING OPTICAL SYSTEM Filed May 15, 1933 INVENTOR lav/Fr IOIVEZPJ .G/IGE ATTO NEY Patented July 30, 1935 2,009,769

REFLECTING OPTICAL I SYSTEM Henry Phelps Gage, Corning, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corporation of New York Application May 15, 1933, Serial No. $71,213

8 Claims. (01. 8882) This invention has for its object to provide an the frame and spaced apart a suitable distance by optical system applicable to reflecting signals and the washer F. One of the discs B which will be signs in which light falling on the anterior face hereinafter termed the reflecting disc has its thereof is reflected back by the system to an obouter surface silvered as at D. The other disc A server stationed adjacent to the line adjoining will be termed the transparent disc. Both discs 5 the light source of the system, giving the appearhave on their interior surface a series of lenance of illumination to the sign or signal. ticular bosses E, forming lenses, which for ef- The invention is characterized by the use of two ficiency should be as closely together on such surlenses oppositely disposed in respecttoeach other, faces as is possible. The discs may be counter- 10 at a distance apart less than the focal length of parts of each other except for the silvering of the 10 either lens with the posterior surface of the second posterior disc. By preference each of the discs lens planar and silvered or otherwise rendered A and B has formed therein on the periphery of reflecting. A plurality of such systems may be its flange a slot 0 or 11 so that by bringing these assembled in a unitary structure by forming slots into registration with each other in the aslenticular bosses, constituting lenses on one face semblage a boss on the one disc will be in line 15 of a disc of glass, (which disc may 1be PIS-n35) with the boss on the other disc. and assembling two such iscs reverse y in a s Two aligned bosses with the mirror backing in able frame with the bossed faces opposite each line therewith constitutes a complete optical sysother and silvering or otherwise rerfdering reflectem which, as is shown in Figures 2, 3, and 4,

tive the outer face of one of such discs. This -reis composed of two piano convex lenses spaced 20 sults in a unitary structure having a smooth anfrom each other by a distance less than the terior face which is of importance in preventing focal length of a boss, and a mirror surface, the the collection of dirt and snow thereon. The mirror surface being the planar face of the constructiorlilfjustt suggestzgdtis tmoreover iclzlonomipOSlLGI'iOli flenas1 situated at approximately the cal to man ac are in a i permi s e conprincipa oc poin o t e doublet formed by struction of a sign of relatively large area from the two lenticular bosses. Under such conditions two pressed discs of glass which may be identical a ray M incident on the anterior face of the in contour and one of which is rendered reflectransparent face of the transparent disc A paraltive. lel with the principal axis of the system and For convenience I will use the term silvered adjacent to such axis (see Figure 3) enters the 30 in this specification to define a surface rendered disc A without suffering refraction, is refracted reflecting by silvering or any other approved by the (lzurved surgace 8f thtehboss towards the manner. principa axis, an en ers e second disc B Referring to the accompanying drawing in without being refracted by the curved surface of which corresponfiingfparfts are designated by corthe fiass E carried thereby. Since the ray was. 35

responding mar s 0 re erence. bent toward the axis by the curved surface of Fi ure 1 is a elevation of the i r ace of the boss E on the disc A and was not refracted (ard ic Sli for use in a System Such 8-518 here upon entering the disc B, it becomes evident that isc ose it will cross the axis at some point in the rear- Figure 2 is a vertical section through two d s f the plate A. By proper adjustment of the 40 P as Shown 1n figure when assembled m a thickness of the washer F the silvered surface sultable frame the outer surface of the of the plate B may be causedto intersect the posfienor d1 sc f axis at the point where the ray M crosses it and Flgure 3 1S dla'gmm musttgatmg the path of hence the ray M will be reflected back through y through lenses sys m Such as the disc B on the side of the axis opposite that in Figure 2 when the incident ray is parallel with h t d d f th the principal axis of the system. w 10 1 en ere an emerge 6 tem as ray M substantially parallel with the axis Figure 4 1s similar to Figure 3 but showmg the course of rays oblique to the principal axis of the as shown m Flgure system 1 ray N from an oblique incident bundle will As Shown in Figures 1 and 2 the complete unit strike the plain outer surface of the disc A, sufconsists of two discs 0f glass A and B and each fer refraction as it enters the disc and be again having a flange a or b surrounding it, offset from g zg gig B i l-l r i s igafii gfi acz d 8;

war e 1 its plane. These discs are assembled in a suitable the front curved surface of the boss E on the 5 frame C, the discs being reversely mounted, in,

disc B and entering the disc B is bent toward the reflecting surface D from whence it is returned through the disc B and is again refracted by the curved surfaces of the bosses E and the flat face of the disc A so that it flnally emerges as ray N substantially parallel with the axis of the oblique bundle.-

In actual practice I have found that when two discs of identical construction are made from a glass having a refractive index of 1.50 the most satisfactory results are obtained when they are assembled with the bosses E'of one plate facing the bosses E of the other plate and the distance S between the plates lies within the limits shown in the following formula in which R is the radius of curvature of the bosses E and .9 R is the thickness of the plates, then While in the foregoing I have shown and described the preferred embodiment of my invention, it is to be understood that minor changes in the details of construction, combination and arrangement of parts may be resorted to without departing from the spirit and scope of my invention as claimed.

Having thus described my invention what I claim and desire to secure by Letters Patent is:

1. A-reflecting system including two cooperating oppositely disposed converging lenses, one of the lenses having both surfaces transparent and the other lens having a transparent curved surface and a plane reflecting surface which in-- tersects the principal axis of the system at its principal focus.

2. A reflecting system including two pianoconvex lenses, the convex faces of which are opposite each other, the plano face of one of the lenses being reflective and intersecting the principal axis of the system at the principal focus of the latter.

3. In a reflecting system, the combination of two discs of transparent material arranged in spaced parallel relation, each disc havin on its interior surface aligning convex faces, the outer face of one of the discs being silvered.

4. In a reflecting structure, the combination with two discs of transparent material, said discs being spaced from each other, each disc having on its inner face a series of bosses forming converging lenses, the lenses on the one disc being opposite the lenses on the other disc, and the outer face of one of the discs intersecting the principal axes of the systems formed by the several pairs of lenses at approximately the principal focal points of such systems and being silvered.

5. In a reflecting system having a focus, a pair of cooperating convex lenses of identical form arranged in axially aligned spaced relation and a reflector on one of said lenses lying in a plane which intersects the axis of the system at the focus. v

6. In a reflecting system a pair of plano-convex lenses of identical form arranged in axially aligned spaced relation with their convex faces toward each other and a reflector on the plane face of one of said lenses, said reflector intersecting the axis of the lens at the point where parallel light projected onto the plane face of the opposite lens is brought into a focus.

7. In a reflecting structure a pair of transparent plates, means to retain the plates in spaced parallel relation, lenticular bosses on the adjacent faces of each plate, the axes of the bosses on one plate aligning with those of the bosses on the other plate and a reflecting coating on the smooth face of one of the plates.

8. In a reflecting structure a pair of disks of transparent material, one disk being the counterpart of the other, each of said disks having bosses on one face forming converging lenses, flanges at the edges of the disks for holding them in spaced parallel relation with the bosses facing one another and in axial alignment and a silvered surface on the plane face of one of the disks.

HENRY PHELPS GAGE. 

